The dynamics of the expectation value of a spin operator (S) over cap (n) in the quantum mechanical Heisenberg model has been compared with the trajectory of the corresponding classical spin S-n. A Hamilton operator (H) over cap linear in the spin operator (S) over cap (n) shows a perfect agreement between quantum mechanical and classical trajectories. Quadratic or higher-order terms in the Hamilton operator lead to disagreement. The corresponding correction term can be found for different physical descriptions and methods dealing with the quantum mechanical Heisenberg model.